1. Field of the Invention
The present invention relates to novel onium borates or borates of organometallic complexes which are cationic initiators of polymerization, to a process for the preparation thereof and to the use of such novel borates for the polymerization or crosslinking of functional polymers or monomers by photochemical activation, or activation under an electron beam.
2. Description of the Prior Art
Onium salts or salts of organometallic complexes are well known to this art as initiators of the cationic polymerization of monomers or of polymers substituted by functional groups of the epoxy or vinyl ether type, or the like (U.S. Pat. Nos. 4,069,054; 4,450,360; 4,576,999 and 4,640,967; Canadian Patent No. 1,274,646; European Application EP-A-203,829).
It has been observed that the best results are obtained when the anion of the initiator salt is SbF.sub.6.sup.- ; the initiator salts containing this type of anion, however, present toxicity risks.
It is also known to this art to use ferrocenium perfluorotetraphenylborates of the bis(.eta..sup.5 -cyclopentadienyl)Fe.sup.+ tetrakis(pentafluorophenyl)borate type for generating catalysts of the Ziegler-Natta variety, which catalysts are then used for polymerizing vinyl monomers (EP-A-481,480; EP-A-468,651; EP-A-418,044; EP-A-468,537; EP-A-421,659 and EP-A-277,044; Makromol. Chem Rapid Commun., 12, 663-667 (1991); Organometallics, 10, 840-842 (1991); it has been observed that the ferrocenium perfluorotetraphenylborates of the bis(.eta..sup.5 -cyclopentadienyl)Fe.sup.+ tetrakis(pentafluorophenyl)borate type are not photoinitiators.